It is known in the technical sector of winding pipes in the form of shanks, reels and the like that said pipes are obtained by winding the reels using coiling machines provided with a rotating reel, the rotating part of which comprises: a drum, rotating about an axis of rotation and formed by circle segments, or “bar elements,” which are parallel to the axis of rotation and displaceable radially from/towards said axis on respective radial arms for adjusting the internal diameter of the spool; and a cross journal, which is formed by radial arms and flanges and is displaceable parallel to the axis of rotation for adjusting the height of the spool. Also known in the art are different models of coilers for automatically coiling pipes made of plastic and other materials, which operate with a completely automatic cycle comprising essentially the following steps:
automatically taking up the pipe to be wound on the reel by means of a corresponding mechanical device;
automatically starting the coiling operation, during which a pipe-guiding device distributes the pipe on the rotating reel;
automatically cutting the pipe when the set winding length is reached;
starting the tying operations for preparing the finished spool;
automatically unloading the wound and tied spool.
It is also known that the rotating reel is secured to the base structure of the machine on one side only and that consequently, during the pipe coiling procedure, the spool being coiled and/or the completed spool is supported in a cantilevered manner by the circle segments (bar elements) of the rotating drum of the reel, such that its weight bears entirely on the said bar elements and, consequently, on the reel structure, with generation of high flexural moments on the bar elements and on the corresponding radial supporting arms thereof. Said moments generated by the cantilevered mass of the reel and the spool frequently result in breakages and/or structural failures of the various reel components. Therefore this configuration of the coiling machine requires continuous adjustment and repairs which result in machine stoppages and inconvenience, with a consequent increase in the corresponding direct costs and final cost of the spool.
A further problem associated with the machines according to the prior art consists in the fact that the aforementioned reel structure tends to have an adverse effect on the end result of the coiling process, resulting in spools which are not perfectly coiled and/or uniform, since the spool being wound with its weight projecting on the reel generates flexural forces on the bar elements and axial misalignment of the winding drum.
The aforementioned reel structure according to the prior art also results in limitation of the final width which may be obtained for the wound spools which may not exceed the limits imposed by the structural strength of the reel in relation to the aforementioned flexural forces and, in addition, coaxial unloading of the spool is made difficult in the known machines.
WO 2010/103336 also discloses a coiling machine for small-diameter pipes which envisages wrapping the finished (small-size and low-weight) spool with stretch film before it is unloaded. The introductory part of the patent application contains an analysis of the machines for coiling larger-diameter pipes in the form of large-size and heavy spools which require tying by means of straps. The machine described in WO2010/103336 consists in particular of a coiling machine for small-size pipes and spools which are wrapped with a film having a width greater than the width of the spool so that the spool is wound by the film also laterally. The machine comprises a reel which is divided into two half-reels, each provided with elements for laterally retaining the spool, which elements must be folded down/retracted during rotation for winding the wrapping film, so as to allow the latter to pass through without breakages and/or tearing. For practical reasons, however, large-size and heavy spools cannot be wrapped with film.